diff options
Diffstat (limited to 'include/linux/buffer_head.h')
| -rw-r--r-- | include/linux/buffer_head.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 58a82f58e44e..894e5d125de6 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -81,11 +81,14 @@ struct buffer_head { /* * macro tricks to expand the set_buffer_foo(), clear_buffer_foo() * and buffer_foo() functions. + * To avoid reset buffer flags that are already set, because that causes + * a costly cache line transition, check the flag first. */ #define BUFFER_FNS(bit, name) \ static __always_inline void set_buffer_##name(struct buffer_head *bh) \ { \ - set_bit(BH_##bit, &(bh)->b_state); \ + if (!test_bit(BH_##bit, &(bh)->b_state)) \ + set_bit(BH_##bit, &(bh)->b_state); \ } \ static __always_inline void clear_buffer_##name(struct buffer_head *bh) \ { \ |